galpy.df.impulse_deltav_plummer¶
- galpy.df.impulse_deltav_plummer(v, y, b, w, GM, rs)[source]¶
NAME:
impulse_deltav_plummer
PURPOSE:
calculate the delta velocity to due an encounter with a Plummer sphere in the impulse approximation; allows for arbitrary velocity vectors, but y is input as the position along the stream
INPUT:
v - velocity of the stream (nstar,3)
y - position along the stream (nstar)
b - impact parameter
w - velocity of the Plummer sphere (3)
GM - mass of the Plummer sphere (in natural units)
rs - size of the Plummer sphere
OUTPUT:
deltav (nstar,3)
HISTORY:
2015-04-30 - Written based on Erkal’s expressions - Bovy (IAS)